[Discrete Math] Finals review problems in Probability

There are a couple of problems which even the discussion board on our University website has not answered:

A variation of the birthday problem:Find the smallest number of people you need to choose at random so that the probability that at least two of them were both born on April 1 exceeds 1/2.

Suppose that the probability that x is in a list of n distinct integers is 2/3 and that it is equally likely that x equals any element in the list. Find the average number of comparisons used by the linear search algorithm to find x or to determine that it is not in the list.

Re: [Discrete Math] Finals review problems in Probability

Hi

I am getting for the first problem and for the second problem.

Last edited by anonimnystefy (2012-12-13 09:01:01)

Here lies the reader who will never open this book. He is forever dead.Taking a new step, uttering a new word, is what people fear most. ― Fyodor Dostoyevsky, Crime and PunishmentThe knowledge of some things as a function of age is a delta function.

Re: [Discrete Math] Finals review problems in Probability

Hi bobbym

They would need 613.

Last edited by anonimnystefy (2012-12-13 09:00:39)

Here lies the reader who will never open this book. He is forever dead.Taking a new step, uttering a new word, is what people fear most. ― Fyodor Dostoyevsky, Crime and PunishmentThe knowledge of some things as a function of age is a delta function.

Re: [Discrete Math] Finals review problems in Probability

The probability that less than 2 people have their birthdays on April 1st is (364/365)^n+n*1/365*(364/365)^(n-1). This probability needs to be less than or equal to 1/2.

Here lies the reader who will never open this book. He is forever dead.Taking a new step, uttering a new word, is what people fear most. ― Fyodor Dostoyevsky, Crime and PunishmentThe knowledge of some things as a function of age is a delta function.

Re: [Discrete Math] Finals review problems in Probability

You are not reading the question!

Here lies the reader who will never open this book. He is forever dead.Taking a new step, uttering a new word, is what people fear most. ― Fyodor Dostoyevsky, Crime and PunishmentThe knowledge of some things as a function of age is a delta function.

Re: [Discrete Math] Finals review problems in Probability

Well, the expected number of people for two birthdays on the 1st of April cannot be less than for one birthday.

Here lies the reader who will never open this book. He is forever dead.Taking a new step, uttering a new word, is what people fear most. ― Fyodor Dostoyevsky, Crime and PunishmentThe knowledge of some things as a function of age is a delta function.

Re: [Discrete Math] Finals review problems in Probability

Now it's okay. Though I changed it 25 minutes ago, and you didn't notice...

Here lies the reader who will never open this book. He is forever dead.Taking a new step, uttering a new word, is what people fear most. ― Fyodor Dostoyevsky, Crime and PunishmentThe knowledge of some things as a function of age is a delta function.

Re: [Discrete Math] Finals review problems in Probability

Well, for the second problem, the book is wrong.

Here lies the reader who will never open this book. He is forever dead.Taking a new step, uttering a new word, is what people fear most. ― Fyodor Dostoyevsky, Crime and PunishmentThe knowledge of some things as a function of age is a delta function.

Re: [Discrete Math] Finals review problems in Probability

I do not know about the 7th edition but the 6th edition has the answer to this problem just a few pages away!

How are you getting (4n+6)/3?

Here lies the reader who will never open this book. He is forever dead.Taking a new step, uttering a new word, is what people fear most. ― Fyodor Dostoyevsky, Crime and PunishmentThe knowledge of some things as a function of age is a delta function.

Re: [Discrete Math] Finals review problems in Probability

On which page is that?

Here lies the reader who will never open this book. He is forever dead.Taking a new step, uttering a new word, is what people fear most. ― Fyodor Dostoyevsky, Crime and PunishmentThe knowledge of some things as a function of age is a delta function.